Sealioning is a type of online harassment or trolling tactic, where someone persistently requests empirical evidence from another user with the intent to exhaust them rather than engage in sincere debate. It's named after a webcomic in which a sea lion follows a character around, constantly demanding proof for a casual statement made in conversation. It's often seen as a form of bad faith argument, as the goal isn't really to get information, but to frustrate or tire out the person being targeted.